<html>
<head>
  <title>Form validation</title>
  <style>
    .error {color: #FF0000;}
  </style>
</head>
<body>
  <?php

  function test_input($data) {
    return $data.'hihihi';
  }

// define variables and set to empty values
  $nameErr = $emailErr = $genderErr = $websiteErr = "";
  $name = $email = $gender = $comment = $website = "";

  if ($_SERVER["REQUEST_METHOD"] == "POST") {
    if (empty($_POST["name"])) {
      $nameErr = "Name is required";
    } else {
      $name = test_input($_POST["name"]);
    }

    if (empty($_POST["email"])) {
      $emailErr = "Email is required";
    } else {
      $email = test_input($_POST["email"]);
    }

    if (empty($_POST["website"])) {
      $website = "";
    } else {
      $website = test_input($_POST["website"]);
    }

    if (empty($_POST["comment"])) {
      $comment = "";
    } else {
      $comment = test_input($_POST["comment"]);
    }

    if (empty($_POST["gender"])) {
      $genderErr = "Gender is required";
    } else {
      $gender = test_input($_POST["gender"]);
    }

  }
  ?>

  <form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">
    Name: <input type="text" name="name">
    <span class="error">* <?php echo $nameErr;?></span>
    <br><br>
    E-mail:
    <input type="text" name="email">
    <span class="error">* <?php echo $emailErr;?></span>
    <br><br>
    Website:
    <input type="text" name="website">
    <span class="error"><?php echo $websiteErr;?></span>
    <br><br>
    <label>Comment: <textarea name="comment" rows="5" cols="40"></textarea>
      <br><br>
      Gender:
      <input type="radio" name="gender" value="female">Female
      <input type="radio" name="gender" value="male">Male
      <span class="error">* <?php echo $genderErr;?></span>
      <br><br>
      <input type="submit" name="submit" value="Submit">
    </form>

    <?php
    echo "<h2>Your Input:</h2>";
    echo $name."<br>";
    echo $email."<br>";
    echo $website."<br>";
    echo $comment."<br>";
    echo $gender."<br>";
    ?>
  </body>
  </html>
